Tissue modification devices and methods of using the same

ABSTRACT

Tissue modification devices are provided. Aspects of the devices include an elongated member having a proximal end and a distal end. The distal end of the elongated member is dimensioned to pass through a minimally invasive body opening and includes a distal end integrated visualization sensor and tissue modifier. In some instances, the devices further include an integrated articulation mechanism that imparts steerability to at least one of the visualization sensor, the tissue modifier and the distal end of the elongated member. Also provided are methods of modifying internal target tissue of a subject using the tissue modification devices.

CROSS-REFERENCE TO RELATED APPLICATION

Pursuant to 35 U.S.C. §119 (e), this application claims priority to U.S.Provisional Application Ser. No. 61/082,774 filed Jul. 22, 2008; thedisclosure of which priority application is herein incorporated byreference.

INTRODUCTION

Traditional surgical procedures, both therapeutic and diagnostic, forpathologies located within the body can cause significant trauma to theintervening tissues. These procedures often require a long incision,extensive muscle stripping, prolonged retraction of tissues, denervationand devascularization of tissue. These procedures can require operatingroom time of several hours and several weeks of post-operative recoverytime due to the destruction of tissue during the surgical procedure. Insome cases, these invasive procedures lead to permanent scarring andpain that can be more severe than the pain leading to the surgicalintervention.

The development of percutaneous procedures has yielded a majorimprovement in reducing recovery time and post-operative pain becauseminimal dissection of tissue, such as muscle tissue, is required. Forexample, minimally invasive surgical techniques are desirable for spinaland neurosurgical applications because of the need for access tolocations within the body and the danger of damage to vital interveningtissues. While developments in minimally invasive surgery are steps inthe right direction, there remains a need for further development inminimally invasive surgical instruments and methods.

SUMMARY

Tissue modification devices are provided. Aspects of the devices includean elongated member having a proximal end and a distal end. The distalend of the elongated member is dimensioned to pass through a minimallyinvasive body opening and includes a distal end integrated visualizationsensor and tissue modifier. In some instances, the devices furtherinclude an integrated articulation mechanism that imparts steerabilityto at least one of the visualization sensor, the tissue modifier and thedistal end of the elongated member. Also provided are methods ofmodifying internal target tissue of a subject using the tissuemodification devices.

BRIEF DESCRIPTION OF THE FIGURES

FIGS. 1A and B provide two different views of a disposable tissuemodification device according to an embodiment of the invention.

FIGS. 2A to 2C provide cross-sectional views of the distal ends ofdevices according to certain embodiments of the invention.

FIGS. 3A to 3E provide cross-sectional views of the distal ends ofdevices according to certain embodiments of the invention.

FIG. 4 provides an alternative view of the distal end of a deviceaccording to an embodiment of the invention, where the device is shownaccessing the nucleus pulposus of an intervertebral disc.

FIG. 5 provides an alternative view of the distal end of a deviceaccording to an embodiment of the invention, where the device is shownaccessing the nucleus pulposus of an intervertebral disc.

FIGS. 6A to 6E provide various views of the distal end of a deviceaccording to one embodiment of the invention.

FIG. 7 provides a cutaway view of the device shown in FIGS. 1A and 1B.

FIG. 8 provides a depiction of a system according to one embodiment ofthe invention, where the system includes both a disposable tissuemodifier device and an extra-corporeal control unit.

FIG. 9 provides a block diagram showing the architecture of a systemaccording to one embodiment of the invention and how that systeminteracts with a user.

FIG. 10 shows a CMOS visualization sub-system that may be incorporatedinto a tissue modification system according to an embodiment of theinvention.

DETAILED DESCRIPTION

Tissue modification devices are provided. Aspects of the devices includean elongated member having a proximal end and a distal end. The distalend of the elongated member is dimensioned to pass through a minimallyinvasive body opening and includes a distal end integrated visualizationsensor and tissue modifier. In some instances, the devices furtherinclude an integrated articulation mechanism that imparts steerabilityto at least one of the visualization sensor, the tissue modifier and thedistal end of the elongated member. Also provided are methods ofmodifying internal target tissue of a subject using the tissuemodification devices.

Before the present invention is described in greater detail, it is to beunderstood that this invention is not limited to particular embodimentsdescribed, as such may, of course, vary. It is also to be understoodthat the terminology used herein is for the purpose of describingparticular embodiments only, and is not intended to be limiting, sincethe scope of the present invention will be limited only by the appendedclaims.

Where a range of values is provided, it is understood that eachintervening value, to the tenth of the unit of the lower limit unlessthe context clearly dictates otherwise, between the upper and lowerlimit of that range and any other stated or intervening value in thatstated range, is encompassed within the invention. The upper and lowerlimits of these smaller ranges may independently be included in thesmaller ranges and are also encompassed within the invention, subject toany specifically excluded limit in the stated range. Where the statedrange includes one or both of the limits, ranges excluding either orboth of those included limits are also included in the invention.

Unless defined otherwise, all technical and scientific terms used hereinhave the same meaning as commonly understood by one of ordinary skill inthe art to which this invention belongs. Although any methods andmaterials similar or equivalent to those described herein can also beused in the practice or testing of the present invention, representativeillustrative methods and materials are now described.

All publications and patents cited in this specification are hereinincorporated by reference as if each individual publication or patentwere specifically and individually indicated to be incorporated byreference and are incorporated herein by reference to disclose anddescribe the methods and/or materials in connection with which thepublications are cited. The citation of any publication is for itsdisclosure prior to the filing date and should not be construed as anadmission that the present invention is not entitled to antedate suchpublication by virtue of prior invention. Further, the dates ofpublication provided may be different from the actual publication dateswhich may need to be independently confirmed.

It is noted that, as used herein and in the appended claims, thesingular forms “a”, “an”, and “the” include plural referents unless thecontext clearly dictates otherwise. It is further noted that the claimsmay be drafted to exclude any optional element. As such, this statementis intended to serve as antecedent basis for use of such exclusiveterminology as “solely,” “only” and the like in connection with therecitation of claim elements, or use of a “negative” limitation.

As will be apparent to those of skill in the art upon reading thisdisclosure, each of the individual embodiments described and illustratedherein has discrete components and features which may be readilyseparated from or combined with the features of any of the other severalembodiments without departing from the scope or spirit of the presentinvention. Any recited method can be carried out in the order of eventsrecited or in any other order which is logically possible.

In further describing various aspects of the invention, aspects ofembodiments of the subject tissue modification devices are describedfirst in greater detail. Next, embodiments of methods of modifying aninternal target tissue of a subject in which the subject tissuemodification devices may find use are reviewed in greater detail.

Tissue Modification Devices

Aspects of the invention include tissue modification devices useful formodifying an internal target tissue site, e.g., a spinal location thatis near or inside of an intervertebral disc (IVD). As summarized above,the tissue modification devices are dimensioned such that at least thedistal end of the devices can pass through a minimally invasive bodyopening. As such, at least the distal end of the devices may beintroduced to an internal target site of a patient, e.g., a spinallocation that is near or inside of an intervertebral disc, through aminimal incision, e.g., one that is less than the size of an incisionemployed for an access device having a outer diameter of 20 mm orsmaller, e.g., less than 75% the size of such an incision, such as lessthan 50% of the size of such an incision, or smaller. In some instances,at least the distal end of the elongated member is dimensioned to passthrough a Cambin's triangle. The Cambin's triangle (also known in theart as the Pambin's triangle) is an anatomical spinal structure boundedby an exiting nerve root and a traversing nerve root and a disc. Theexiting root is the root that leaves the spinal canal just cephalad(above) the disc, and the traversing root is the root that leaves thespinal canal just caudad (below) the disc. Where the distal end of theelongated member is dimensioned to pass through a Cambin's triangle, atleast the distal end of the device has a longest cross-sectionaldimension that is 10 mm or less, such as 8 mm or less and including 7 mmor less. In some instances, the elongated member has an outer diameterthat is 7.5 mm or less, such as 7.0 mm or less, including 6.7 mm orless, such as 6.6 mm or less, 6.5 mm or less, 6.0 mm or less, 5.5 mm orless, 5.0 mm or less.

As summarized above, tissue modification devices of the inventioninclude an elongated member. As this component of the devices iselongated, it has a length that is 1.5 times or longer than its width,such as 2 times or longer than its width, including 5 or even 10 timesor longer than its width, e.g., 20 times longer than its width, 30 timeslonger than its width, or longer. The length of the elongated member mayvary, an in some instances ranges from 5 cm to 20 cm, such as 7.5 cm to15 cm and including 10 to 12 cm. The elongated member may have the sameouter cross-sectional dimensions (e.g., diameter) along its entirelength. Alternatively, the cross-sectional diameter may vary along thelength of the elongated member.

The elongated members of the subject tissue modification devices have aproximal end and a distal end. The term “proximal end”, as used herein,refers to the end of the elongated member that is nearer the user (suchas a physician operating the device in a tissue modification procedure),and the term “distal end”, as used herein, refers to the end of theelongated member that is nearer the internal target tissue of thesubject during use. The elongated member is, in some instances, astructure of sufficient rigidity to allow the distal end to be pushedthrough tissue when sufficient force is applied to the proximal end ofthe elongate member. As such, in these embodiments the elongated memberis not pliant or flexible, at least not to any significant extent.

Depending on the particular device embodiment, the elongated member mayor may not include one or more lumens that extend at least partiallyalong its length. When present, the lumens may vary in diameter and maybe employed for a variety of different purposes, such as irrigation,aspiration, electrical isolation (for example of conductive members,such as wires), as a mechanical guide, etc., as reviewed in greaterdetail below. When present, such lumens may have a longest cross sectionthat varies, ranging in some in stances from 0.5 to 5.0 mm, such as 1.0to 4.5 mm, including 1.0 to 4.0 mm. The lumens may have any convenientcross-sectional shape, including but not limited to circular, square,rectangular, triangular, semi-circular, trapezoidal, irregular, etc., asdesired. These lumens may be provided for a variety of differentfunctions, including as irrigation and/or aspiration lumens, asdescribed in greater detail below.

As summarized above, the devices include a distal end integratedvisualization sensor and a distal end integrated tissue modifier. As thevisualization sensor is integrated at the distal end of the device, itcannot be removed from the remainder of the device without significantlycompromising the structure and functionality of the device. Accordingly,the devices of the present invention are distinguished from deviceswhich include a “working channel” through which a separate autonomousdevice, such as a tissue modifier, is passed through. In contrast tosuch devices, since the visualization sensor of the present device isintegrated at the distal end, it is not a separate device from theelongated member that is merely present in a working channel of theelongated member and which can be removed from the working channel ofsuch an elongated member without structurally compromising the elongatedmember in any way. The visualization sensor may be integrated with thedistal end of the elongated member by a variety of differentconfigurations. Integrated configurations include configurations wherethe visualization sensor is fixed relative to the distal end of theelongated member, as well as configurations where the visualizationsensor is movable to some extent relative to the distal end of theelongated member. Movement of the visualizations sensor may also beprovided relative to the distal end of the elongated member, but thenfixed with respect to another component present at the distal end, suchas a distal end integrated tissue modifier. Specific configurations ofinterest are further described below in connection with the figures.

Visualization sensors of interest include miniature imaging sensors thathave a cross-sectional area which is sufficiently small for its intendeduse and yet retains a sufficiently high matrix resolution. Imagingsensors of interest are those that include a photosensitive component,e.g., array of photosensitive elements that convert light intoelectrons, coupled to an integrated circuit. The integrated circuit maybe configured to obtain and integrate the signals from thephotosensitive array and output image data, which image data may in turnbe conveyed to an extra-corporeal device configured to receive the dataand display it to a user. The image sensors of these embodiments may beviewed as integrated circuit image sensors. The integrated circuitcomponent of these sensors may include a variety of different types offunctionalities, including but not limited to: image signal processing,memory, and data transmission circuitry to transmit data from thevisualization sensor to an extra-corporeal location, etc. The miniatureimaging sensors may further include a lens component made up of one ormore lenses positioned relative to the photosensitive component so as tofocus images on the photosensitive component. Where desired, the one ormore lenses may be present in a housing. Specific types of miniatureimaging sensors of interest include complementarymetal-oxide-semiconductor (CMOS) sensors and charge-coupled device (CCD)sensors. The sensors may have any convenient configuration, includingcircular, square, rectangular, etc. Visualization sensors of interestmay have a longest cross-sectional dimension that varies depending onthe particular embodiment, where in some instances the longest crosssectional dimension (e.g., diameter) is 4.0 mm or less, such as 3.5 mmor less, including 3.0 mm or less, such as 2.5 mm or less, including 2.0mm or less, including 1.5 mm or less, including 1.0 mm or less.

Imaging sensors of interest may be either frontside or backsideillumination sensors, and have sufficiently small dimensions whilemaintaining sufficient functionality to be integrated at the distal endof the elongated members of the devices of the invention. Aspects ofthese sensors are further described in one or more the following U.S.Patents, the disclosures of which are herein incorporated by reference:U.S. Pat. Nos. 7,388,242; 7,368,772; 7,355,228; 7,345,330; 7,344,910;7,268,335; 7,209,601; 7,196,314; 7,193,198; 7,161,130; and 7,154,137.

As the visualization sensor is a distal end integrated visualizationsensor, it is located at or near the distal end of the elongated member.Accordingly, it is positioned at 3 mm or closer to the distal end, suchas at 2 mm or closer to the distal end, including at 1 mm or closer tothe distal end. In some instances, the visualization sensor is locatedat the distal end of the elongated member. The visualization sensor mayprovide for front viewing and/or side-viewing, as desired. Accordingly,the visualization sensor may be configured to provide image data as seenin the forward direction from the distal end of the elongated member.Alternatively, the visualization sensor may be configured to provideimage data as seen from the side of the elongate member. In yet otherembodiments, a visualization sensor may be configured to provide imagedata from both the front and the side, e.g., where the image sensorfaces at an angle that is less than 90° relative to the longitudinalaxis of the elongated member, e.g., as illustrated in FIGS. 6A to 6C,described in greater detail below.

Because the visualization sensor is a distal end integratedvisualization sensor, the visualization sensor also includesfunctionality for conveying image data to an extra-corporeal device,such as an image display device. In some instances, a signal cable (orother type of signal conveyance element) may be present to connect theimage sensor at the distal end to a device at the proximal end of theelongate member, e.g., in the form of one or more wires running alongthe length of the elongate member from the distal to the proximal end.Alternatively, wireless communication protocols may be employed, e.g.,where the imaging sensor is operatively coupled to a wireless datatransmitter, which may be positioned at the distal end of the elongatedmember (including integrated into the visualization sensor, at someposition along the elongated member or at the proximal end of thedevice, e.g., at a location of the proximal end of the elongated memberor associated with the handle of the device).

Where desired, the devices may include one or more illumination elementsconfigured to illuminate a target tissue location so that the locationcan be visualized with a visualization sensor, e.g., as described above.A variety of different types of light sources may be employed asillumination elements, so long as their dimensions are such that theycan be positioned at the distal end of the elongated member. The lightsources may be integrated with a given component (e.g., elongatedmember) such that they are configured relative to the component suchthat the light source element cannot be removed from the remainder ofthe component without significantly compromising the structure of thecomponent. As such, the integrated illumination element of theseembodiments is not readily removable from the remainder of thecomponent, such that the illumination element and remainder of thecomponent form an inter-related whole. The light sources may be lightemitting diodes configured to emit light of the desired wavelengthrange, or optical conveyance elements, e.g., optical fibers, configuredto convey light of the desired wavelength range from a location otherthan the distal end of the elongate member, e.g., a location at theproximal end of the elongate member, to the distal end of the elongatemember. As with the image sensors, the light sources may include aconductive element, e.g., wire, or an optical fiber, which runs thelength of the elongate member to provide for power and control of thelight sources from a location outside the body, e.g., an extracorporealcontrol device. Where desired, the light sources may include a diffusionelement to provide for uniform illumination of the target tissue site.Any convenient diffusion element may be employed, including but notlimited to a translucent cover or layer (fabricated from any convenienttranslucent material) through which light from the light source passesand is thus diffused. In those embodiments of the invention where thesystem includes two or more illumination elements, the illuminationelements may emit light of the same wavelength or they may be spectrallydistinct light sources, where by “spectrally distinct” is meant that thelight sources emit light at wavelengths that do not substantiallyoverlap, such as white light and infra-red light. In certainembodiments, an illumination configuration as described in copendingU.S. application Ser. Nos. 12/269,770 and 12/269,772 (the disclosures ofwhich are herein incorporated by reference) is present in the device.

In addition to a distal end integrated visualization sensor, devices ofthe invention further include an integrated distal end tissue modifier.As the tissue modifier is integrated at the distal end of the device, itcannot entirely be removed from the remainder of the device withoutsignificantly compromising the structure and functionality of thedevice. While the tissue modifier cannot entirely be removed from thedevice without compromising the structure and functionality of thedevice, components of the tissue modifier may be removable andreplaceable. For example, an RF electrode tissue modifier may beconfigured such that the wire component of the tissue modifier may bereplaceable while the remainder of the tissue modifier is not.Accordingly, the devices of the present invention are distinguished fromdevices which include a “working channel” through which a separateautonomous tissue modifier device, such as autonomous RF electrodedevice, is passed through. In contrast to such devices, since the tissuemodifier of the present device is integrated at the distal end, it isnot a separate device from the elongated member that is merely presentin a working channel of the elongated member and which can be removedfrom the working channel of such an elongated member withoutstructurally compromising the elongated member in any way. The tissuemodifier may be integrated with the distal end of the elongated memberby a variety of different configurations. Integrated configurationsinclude configurations where the tissue modifier is fixed relative tothe distal end of the elongated member, as well as configurations wherethe tissue modifier is movable to some extent relative to the distal endof the elongated member may be employed in devices of the invention.Specific configurations of interest are further described below inconnection with the figures. As the tissue modifier is a distal endintegrated tissue modifier, it is located at or near the distal end ofthe elongated member. Accordingly, it is positioned at 10 mm or closerto the distal end, such as at 5 mm or closer to the distal end,including at 2 mm or closer to the distal end. In some instances, thetissue modifier is located at the distal end of the elongated member.

Tissue modifiers are components that interact with tissue in some mannerto modify the tissue in a desired way. The term modify is used broadlyto refer to changing in some way, including cutting the tissue, ablatingthe tissue, delivering an agent(s) to the tissue, freezing the tissue,etc. As such, of interest as tissue modifiers are tissue cutters, tissueablators, tissue freezing/heating elements, agent delivery devices, etc.Tissue cutters of interest include, but are not limited to: blades,liquid jet devices, lasers and the like. Tissue ablators of interestinclude, but are not limited to ablation devices, such as devices fordelivery ultrasonic energy (e.g., as employed in ultrasonic ablation),devices for delivering plasma energy, devices for deliveringradiofrequency (RF) energy, devices for delivering microwave energy,etc. Energy transfer devices of interest include, but are not limitedto: devices for modulating the temperature of tissue, e.g., freezing orheating devices, etc. In some embodiments, the tissue modifier is not atissue modifier that achieves tissue modification by clamping, claspingor grasping of tissue such as may be accomplished by devices that traptissue between opposing surfaces (e.g., jaw-like devices). In theseembodiments, the tissue modification device is not an element that isconfigured to apply mechanical force to tear tissue, e.g., by trappingtissue between opposing surfaces. In some embodiments, tissuemodification comprises an action other than just removal by low pressureirrigation or aspiration, for example where some other act is performedon the tissue beyond low pressure irrigation and/or aspiration. In someembodiments, the tissue modifier is distinct from a probe element ordevice that is configured to move tissue without any modification to thetissue other than simple displacement or repositioning, such as throughretraction, atraumatic movement, etc.

In some instances, the tissue modifier includes at least one electrode.For example, tissue modifiers of interest may include RF energy tissuemodifiers, which include at least one electrode and may be configured ina variety of different ways depending on the desired configuration ofthe RF circuit. An RF circuit can be completed substantially entirely attarget tissue location of interest (bipolar device) or by use of asecond electrode attached to another portion of the patient's body(monopolar device). In either case, a controllable delivery of RF energyis achieved. Aspects of the subject tissue modification devices includea radiofrequency (RF) electrode positioned at the distal end of theelongated member. RF electrodes are devices for the delivery ofradiofrequency energy, such as ultrasound, microwaves, and the like. Insome instances, the RF electrode is an electrical conductor fordelivering RF energy to a particular location, such as a desired targettissue. For instance, in certain cases, the RF electrode can be an RFablation electrode. RF electrodes of the subject tissue modificationdevices can include a conductor, such as a metal wire, and can bedimensioned to access an intervertebral disc space. RF electrodes may beshaped in a variety of different formats, such as circular, square,rectangular, oval, etc. The dimensions of such electrodes may vary,where in some embodiments they RF electrode has a longestcross-sectional dimension that is 7 mm or less, 6 mm or less 5 mm orless, 4 mm or less, 3 mm or less or event 2 mm or less, as desired.Where the electrode includes a wire, the diameter of the wire in suchembodiments may be 180 μm, such as 150 μm or less, such as 130 μm orless, such as 100 μm or less, such as 80 μm or less. A variety ofdifferent RF electrode configurations suitable for use in tissuemodification and include, but are not limited to, those described inU.S. Pat. Nos. 7,449,019; 7,137,981; 6,997,941; 6,837,887; 6,241,727;6,112,123; 6,607,529; 5,334,183. RF electrode systems or componentsthereof may be adapted for use in devices of the present invention (whencoupled with guidance provided by the present specification) and, assuch, the disclosures of the RF electrode configurations in thesepatents are herein incorporated by reference. Specific RF electrodeconfigurations of interest are further described in connection with thefigures, below.

In some instances, the tissue modifier is supplied with current from anRF energy source. The voltage signal driving the current to the tissuemodifier may be definable as a sine, square, saw-tooth, triangle, pulse,non-standard, complex, or irregular waveform, or the like, with awell-defined operating frequency. For example, the operating frequencycan range from 1 KHz to 50 MHz, such as from 100 KHz to 25 MHz, andincluding from 250 KHz to 10 MHz. In some embodiments, the RF voltagesignal is a sine wave with operating frequency 460 kHz. Furthermore, thetissue modifier's operating frequency can be modulated by a modulationwaveform. By “modulated” is meant attenuated in amplitude by a secondwaveform, such as a periodic signal waveform. The modulation waveformmay be definable as a sine, square, saw-tooth, triangle, pulse,non-standard, complex, or irregular waveform, or the like, with awell-defined modulation frequency. For example, the modulation frequencycan range from 1 Hz to 10 kHz, such as from 1 Hz to 500 Hz, andincluding from 10 Hz to 100 Hz. In some embodiments, the modulationwaveform is a square wave with modulation frequency 70 Hz.

In some embodiments, a RF tuner is included as part of the RF energysource. The RF tuner includes basic electrical elements (e.g.,capacitors and inductors) which serve to tailor the output impedance ofthe RF energy source. The term “tailor” is intended here to have a broadinterpretation, including affecting an electrical response that achievesmaximum power delivery, affecting an electrical response that achievesconstant power (or voltage) level under different loading conditions,affecting an electrical response that achieves different power (orvoltage) levels under different loading conditions, etc. Furthermore,the elements of the RF tuner can be chosen so that the output impedanceis dynamically tailored, meaning the RF tuner self-adjusts according tothe load impedance encountered at the electrode tip. For instance, theelements may be selected so that the electrode has adequate voltage todevelop a plasma corona when the electrode is placed in a salinesolution (with saline solution grounded to return electrode), but thenmay self-adjust the voltage level to a lower threshold when theelectrode contacts tissue (with tissue also grounded to returnelectrode, for example through the saline solution), thus dynamicallymaintaining the plasma corona at the electrode tip while minimizing thepower delivered to the tissue and the thermal impact to surroundingtissue. RF tuners, when present, can provide a number of advantages. Forexample, delivering RF energy to target tissue through the distal tip ofthe electrode is challenging since RF energy experiences attenuation andreflection along the length of the conductive path from the RF energysource to the electrode tip, which can result in insertion loss.Inclusion of a RF tuner, e.g., as described above, can help to minimizeand control insertion loss.

Devices of the invention may include a linear mechanical actuator forlinearly translating a distal end element of the device, such as thetissue modifier (e.g., a RF electrode) relative to the distal end of theelongate member. By “linearly translating” is meant moving the tissuemodifier along a substantially straight path. As used herein, the term“linear” also encompasses movement of the tissue modifier in anon-straight (i.e., curved) path. For instance, the path of movement ofthe tissue modifier can be deflected from a substantially straight pathif the electrode encounters a tissue of a different density (such as,cartilage, bone, etc.), or if the conformation of the tissue theelectrode is passing through is not straight, etc.

When actuated by a linear mechanical actuator, the tissue modifier iscyclically displaced from a “neutral” position along its axial extensionto positions displaced distally or proximally from the neutral position,with maximum displacement from the neutral position corresponding to thevibratory amplitude. Thus, the linear mechanical actuator actuates thetissue modifier through a distance equal to twice the vibratoryamplitude and ranging from a distal extreme position to a proximalextreme position. In certain embodiments, the tissue modifier can beextended by the linear mechanical actuator from the distal end of theelongated member by 0.1 mm or more, such as 0.5 mm or more, including 1mm or more, for instance 2 mm or more, such as 5 mm or more. This backand forth movement of the tissue modifier relative to the distal end ofthe elongated member that is implemented by the linear mechanicalactuator is described herein in terms of linear translation frequency.It is noted that the above described distal and proximal extremepositions refer to those positions implemented solely by the linearmechanical actuator. In some embodiments,.the linear mechanical actuatormay be the only means for translating the electrode. In otherembodiments, e.g., as described in greater detail below, the linearmechanical actuator may provide vibratory amplitude that is superimposedon another independent control over electrode translation which movesthe electrode over a distance significantly greater than the vibratoryamplitude, e.g. 10 mm or more, such as 20 mm or more, including 30 mm ormore, for instance 40 mm or more. In this case, the tissue modifier maybe extended beyond the range defined by the above described linearmechanical actuator distal and proximal extreme positions. For example,a manual control (e.g., a thumbwheel or analogous structure) may beprovided on the device which permits a user to move the tissue modifierrelative to the distal end in a movement that is distinct from thatprovided by the linear mechanical actuator.

Accordingly, devices of the invention may include a linear mechanicalactuator configured to linearly translate the tissue modifier relativeto the distal end at linear translation frequency. The linear mechanicalactuator can be any of a variety of actuators convenient for use in thesubject devices for linearly translating the tissue modifier relative tothe distal end of the elongated member. For instance, the linearmechanical actuator can be a voice coil motor (VCM), solenoid, pneumaticactuator, electric motor, etc. The linear mechanical actuator isoperatively coupled to the tissue modifier. By “operatively coupled” ismeant that the linear mechanical actuator is connected to the tissuemodifier such that linear movement by the actuator is transferred to thetissue modifier thereby extending the tissue modifier from the distalend of the elongated member or retracting the tissue modifier towardsthe distal end of the elongated member depending on the direction ofmovement by the linear actuator.

When present, the linear actuator provides for linear translation of thetissue modifier at a linear translation frequency. In some instances,the linear translation frequency is 10 Hz or greater, such as 25 Hz orgreater, including 50 Hz or greater, such as 100 Hz or greater. In someembodiments, the linear translation frequency is 70 Hz. In certaincases, the translation of the tissue modifier between the distal andproximal extreme positions occurs with a predetermined lineartranslation frequency while in other embodiments the linear translationfrequency may not be predetermined. The translation frequency (whetheror not predetermined) may depend on various factors, such as but notlimited to, the type of tissue being modified, the amount of tissuebeing modified, the location of the tissue, the proximity of surroundingtissues, the conformation of the tissue, the type of procedure beingperformed, the nature of the linear mechanical actuator, the DC voltageapplied to the actuator, the amplitude of the AC voltage applied to theactuator, etc. For example, in certain embodiments, the lineartranslation frequency is definable as a standard waveform, such as asine waveform. In some cases, the sine waveform is an Hz sine waveform,such that the linear translation frequency ranges from 1 Hz to 500 Hz,such as from 1 Hz to 250 Hz, and including from 10 Hz to 100 Hz. Inother cases, the linear translation frequency is definable as anon-standard, complex, or irregular waveform, or the like. For example,the linear translation frequency can be definable as a waveformcomprising periods that have varying frequencies, a waveform comprisingperiods that have varying amplitudes, a waveform comprising periods thathave varying frequencies and varying amplitudes, a superposition of twoor more waveforms, and the like.

In some embodiments, the tissue modification device is configured tosynchronize the linear mechanical actuation with the modulated RFwaveform. By “synchronize” is meant that two or more events are timed tooperate in a coordinated manner. For example, two or more waveforms canbe timed to operate in a coordinated manner. In some embodiments, themodulation frequency equals the linear translation frequency, and themodulation waveform is phase-shifted relative to the linear translationwaveform. Synchronization of these waveforms may be achieved using avariety of different protocols and may implement one or more controllersof different formats, including hardware, software, and combinationsthereof. For instance, a single common controller may generate twowaveforms that are phase-shifted; alternatively, separate controllerscan be arranged in a master-slave configuration to generate twowaveforms that are phase-shifted, alternatively, one controller cangenerate a waveform, hardware (e.g., an opto-electronic encoder, amechanical encoder, a hall sensor, or the like) can be used to triggeron a physical embodiment (such as mechanical rotation) of that waveform,and a second controller can generate a second waveform with adjustablephase shift from the trigger signal. The phase shift of the modulationwaveform relative to the linear translation waveform can be positive(phase lead) or negative (phase lag), and can have magnitude 0° to 360°or more, such as 0° to 180°, including 60° to 120°. In certainembodiments of the invention, the modulation waveform lags the lineartranslation waveform by 90°.

As discussed above, the tissue modifier (e.g., a RF electrode) hasdistal and proximal extreme positions of its cyclic linear translation.In certain embodiments, the tissue modifier is configured to deliver RFenergy to an internal target tissue while at a position other than thedistal extreme position. Thus, in these cases, the modulation waveformis synchronized with the linear translation waveform such that thetissue modifier is energized when the tissue modifier is at a positionother than the distal extreme position, such as while the tissuemodifier is at or near the proximal extreme position. For example, asdiscussed above, the modulating waveform may be phase-shifted relativeto the linear translation waveform.

Cyclic linear translation of the tissue modification device canfacilitate a variety of functions with multiple benefits. For instance,cyclic linear translation of the tissue modifier at a fast rate relativeto manually controlled translation (e.g., at a frequency greater than 10Hz) will tend to physically advance the tissue modifier into soft tissuedue to the compliance of the soft tissue, while hard tissue will resistdeformation and will thus not allow the tissue modifier to physicallyadvance into the hard tissue. Consequently, the electrode will push backagainst the elongated body as it encounters hard tissue, thus producingtactile feedback to the user. In some embodiments, synchronization ofthe tissue modifier's modulation waveform with its linear translationwaveform provides additional benefits. For instance, rapid retraction ofthe electrode from hard tissue that it encounters will leave the tissuemodifier physically separated from the hard tissue by a gap as thetissue modifier approaches the proximal extreme position. In someembodiments, the tissue modifier tip is activated only when the tissuemodifier is at or near the proximal extreme position, as mentionedabove. This has the effect of preferentially delivering the tissuemodification energy to soft, compliant tissue as opposed to hard, stifftissue. Stated otherwise, this provides tissue discrimination based onelastic modulus. In the case of spinal surgery applications requiringremoval of nuclear material, such as fusion, total disc replacement, andpartial disc replacement, synchronization of the modulation waveformwith the linear translation waveform facilitates the delivery of tissuemodification energy to the nucleus pulposus (soft, compliant tissue)while minimizing the delivery of tissue modification energy to the discannulus (hard, stiff tissue) and the endplates of the vertebral bodies(hard, stiff tissue). In addition, cyclic linear translation of thetissue modifier helps to prevent a condition where the electrode sticksto tissue as it ablates it, resulting in increased thermal effects tothe surrounding tissue, ineffective or discontinuous tissue dissection,buildup of charred or otherwise modified tissue on the tissue modifiertip, or a combination thereof. Additionally, cyclic linear translationof the tissue modifier helps chop the dissected tissue into smallerpieces, thus facilitating aspiration of the dissected tissue.

Depending on the nature of the tissue modifier, the devices will includeproximal end connectors for operatively connecting the device and tissuemodifier to extra-corporeal elements required for operability of thetissue modifier, such as extra-corporeal RF controllers, mechanicaltissue cutter controllers, liquid jet controllers, etc.

In some embodiments, an integrated articulation mechanism that impartssteerability to at least one of the visualization sensor, the tissuemodifier and the distal end of the elongated member is also present inthe device. By “steerability” is meant the ability to maneuver or orientthe visualization sensor, tissue modifier and/or distal end of theelongated member as desired during a procedure, e.g., by using controlspositioned at the proximal end of the device. In these embodiments, thedevices include a steerability mechanism (or one or more elementslocated at the distal end of the elongated member) which renders thedesired distal end component maneuverable as desired through proximalend control. As such, the term “steerability”, as used herein, refers toa mechanism that provides a user steering functionality, such as theability to change direction in a desired manner, such as by moving left,right, up or down relative to the initial direction. The steeringfunctionality can be provided by a variety of different mechanisms.Examples of suitable mechanisms include, but are not limited to one ormore wires, tubes, plates, meshes or combinations thereof, made fromappropriate materials, such as shape memory materials, music wire, etc.In some instances, the distal end of the elongated member is providedwith a distinct, additional capability that allows it to beindependently rotated about its longitudinal axis when a significantportion of the operating handle is maintained in a fixed position, asdiscussed in greater detail below. The extent of distal componentarticulations of the invention may vary, such as from −180 to +180°;e.g., −90 to +90°. Alternatively, the distal probe tip articulations mayrange from 0 to 360°, such as 0 to +180°, and including 0 to +90°, withprovisions for rotating the entire probe about its axis so that the fullrange of angles is accessible on either side of the axis of the probe,e.g., as described in greater detail below. Articulation mechanisms ofinterest are further described in published PCT Application PublicationNos. WO 2009029639; WO 2008/094444; WO 2008/094439 and WO 2008/094436;the disclosures of which are herein incorporated by reference. Specificarticulation configurations of interest are further described inconnection with the figures, below.

In certain embodiments, devices of the invention may further include anirrigator and aspirator configured to flush an internal target tissuesite and/or a component of the device, such as a lens of thevisualization sensor. As such, the elongated member may further includeone or more lumens that run at least the substantial length of thedevice, e.g., for performing a variety of different functions, assummarized above. In certain embodiments where it is desired to flush(i.e., wash) the target tissue site at the distal end of the elongatedmember (e.g. to remove ablated tissue from the location, etc.), theelongated member may include both irrigation lumens and aspirationlumens. Thus, the tissue modification device can comprise an irrigationlumen located at the distal end of the elongated member, and the tissuemodification device can include an aspiration lumen located at thedistal end of the elongated member. During use, the irrigation lumen isoperatively connected to a fluid source (e.g., a physiologicallyacceptable fluid, such as saline) at the proximal end of the device,where the fluid source is configured to introduce fluid into the lumenunder positive pressure, e.g., at a pressure ranging from 0 psi to 60psi, so that fluid is conveyed along the irrigation lumen and out thedistal end. While the dimensions of the irrigation lumen may vary, incertain embodiments the longest cross-sectional dimension of theirrigation lumen ranges from 0.5 mm to 5 mm, such as 0.5 mm to 3 mm,including 0.5 mm to 1.5 mm. During use, the aspiration lumen isoperatively connected to a source of negative pressure (e.g., a vacuumsource) at the proximal end of the device. While the dimensions of theaspiration lumen may vary, in certain embodiments the longestcross-sectional dimension of the aspiration lumen ranges from 1 mm to 7mm, such as 1 mm to 6 mm, including 1 mm to 5 mm. In some embodiments,the aspirator comprises a port having a cross-sectional area that is 33%or more, such as 50% or more, including 66% or more, of thecross-sectional area of the distal end of the elongated member. In someinstances, the negative pressure source is configured to draw fluidand/or tissue from the target tissue site at the distal end into theaspiration lumen under negative pressure, e.g., at a negative pressureranging from 300 to 600 mmHg, such as 550 mmHg, so that fluid and/ortissue is removed from the tissue site and conveyed along the aspirationlumen and out the proximal end, e.g., into a waste reservoir. In certainembodiments, the irrigation lumen and aspiration lumen may be separatelumens, while in other embodiments, the irrigation lumen and theaspiration lumen can be included in a single lumen, for example asconcentric tubes with the inner tube providing for aspiration and theouter tube providing for irrigation. When present, the lumen or lumensof the flushing functionality of the device may be operatively coupledto extra-corporeal irrigation devices, such as a source of fluid,positive and negative pressure, etc. Where desired, irrigators and/oraspirators may be steerable, as described above.

Where desired, the devices may include a control structure, such as ahandle, operably connected to the proximal end of the elongated member.By “operably connected” is meant that one structure is in communication(for example, mechanical, electrical, optical connection, or the like)with another structure. When present, the control structure (e.g.,handle) is located at the proximal end of the device. The handle mayhave any convenient configuration, such as a hand-held wand with one ormore control buttons, as a hand-held gun with a trigger, etc., whereexamples of suitable handle configurations are further provided below.

In some embodiments, the distal end of the elongated member is rotatableabout its longitudinal axis when a significant portion of the operatinghandle is maintained in a fixed position. As such, at least the distalend of the elongated member can turn by some degree while the handleattached to the proximal end of the elongated member stays in a fixedposition. The degree of rotation in a given device may vary, and mayrange from 0 to 360°, such as 0 to 270°, including 0 to 180°.

Devices of the invention may be disposable or reusable. As such, devicesof the invention may be entirely reusable (e.g., be multi-use devices)or be entirely disposable (e.g., where all components of the device aresingle-use). In some instances, the device can be entirely reposable(e.g., where all components can be reused a limited number of times).Each of the components of the device may individually be single-use, oflimited reusability, or indefinitely reusable, resulting in an overalldevice or system comprised of components having differing usabilityparameters.

Devices of the invention may be fabricated using any convenientmaterials or combination thereof, including but not limited to: metallicmaterials such as tungsten, stainless steel alloys, platinum or itsalloys, titanium or its alloys, molybdenum or its alloys, and nickel orits alloys, etc; polymeric materials, such as polytetrafluoroethylene,polyimide, PEEK, and the like; ceramics, such as alumina (e.g.,STEATITE™ alumina, MAECOR™ alumina), etc.

Various aspects of device embodiments of the invention have beendescribed in varying detail above. Device embodiments will now bedescribed in further detail in terms of figures. FIGS. 1A and 1B providetwo different side views of a device 100 according to one embodiment ofthe invention. Device 100 includes an elongated member 110 and anoperating handle 120 at the proximal end of the elongated member 110.The operating handle has a gun configuration and includes a trigger 125and thumbwheel 130 which provide a user with manual operation overcertain functions of the device, e.g., RF electrode positioning andextension. Located at the distal end of the elongated member is anintegrated visualization sensor 140 and tissue modifier 150. Controlelements 160 (which may include aspiration and irrigation lumens,control/power wires, etc.) exit the handle 120 at the distal end region170, which region 170 is rotatable relative to the remainder of thehandle 120. A variety of additional components may be present at thedistal end of the elongated member, which additional elements mayinclude irrigators, aspirators, articulation mechanisms, etc. asdescribed generally above. More details regarding the distal end ofelongate member 140 may be seen in FIG. 6D.

FIGS. 2A to 2C provide cross-sectional views of the distal ends ofelongated members according to three different embodiments of thedevice. Each of these views shows how the visualization sensor andtissue modifier may be integrated at the distal end despite the limitedsize of the distal end.

FIG. 2A shows an example cross-section of the distal end 200 of anelongated member of a device according one embodiment of the invention.Distal end 200 includes an integrated CMOS visualization sensor 210,which has a 2.5 mm diameter. Also shown are guide-wires 215 which have a1 mm diameter and provide for articulation of the distal end of thedevice. Integrated mechanical cutter 230 has a 1.58 mm diameter. Lightsource 240 has a 1.33 mm diameter. Also shown is lumen 250 whichprovides for aspiration and irrigation. FIG. 2A is drawn to scale,demonstrating that integrated visualization, tissue modification,illumination and irrigation can be positioned at the distal end of anelongated member that has a 5.00 mm outer diameter.

FIG. 2B shows the cross-section of a distal end of elongated member thatis analogous to that shown in FIG. 2A, with the exception that smallerdiameter guidewires (0.80 mm) are employed. As a result, light source240 may have a 1.50 mm diameter and mechanical cutter 230 may have a1.92 mm diameter. Like the embodiment shown in FIG. 2A, FIG. 2B is drawnto scale, demonstrating that integrated visualization, tissuemodification, illumination and irrigation can be positioned at thedistal end of an elongated member that has a 5.00 mm outer diameter.

FIG. 2C shows the cross-section of a distal end of elongated member thatis analogous to that shown in FIG. 2A, with the exception that smallernon-circular cross-section guidewires (1.20 mm×0.60 mm) are present. Asa result, light source 240 may have a 1.63 mm diameter and mechanicalcutter 230 may have a 2.22 mm diameter. Like the embodiment shown inFIG. 2A, FIG. 2C is drawn to scale, demonstrating that integratedvisualization, tissue modification, illumination and irrigation can bepositioned at the distal end of an elongated member that has a 5.00 mmouter diameter.

FIG. 3A shows an example cross-section a distal end of a deviceaccording to an embodiment of the invention. FIG. 3A illustrates thedistal end of a device 300 having a distal end outer diameter of 6.6 mm,where the drawing is to scale. The distal end of device 300 includes anintegrated camera 320 (e.g., a CMOS sensor) having an outer diameter of2.8 mm and two fiber optic light sources 330 each having an outerdiameter of 1.3 mm. Also integrated at the distal end are electrodecutters 340 (having dimensions of 2.0 mm×0.7 mm) each associated with anirrigation lumen 350 (having dimensions of 1.2 mm×0.8 mm). In addition,the distal end includes central aspiration lumen 360 which has arectangular configuration and dimensions of 5.0 mm×1.8 mm. In FIG. 3A,the integrated camera 320 is overlapping with other elements, whichillustrates how the camera cross-section only occupies space at the mostdistal portion of the device 300. Overlapping portions of cross sectionsof other components, including the aspiration lumen 360, would beterminated or diverted laterally before reaching the proximal end of thecamera. During use of the device for removal of tissue from a targettissue location, the following steps may be performed. First the distalend 300 of the device is introduced into the target tissue dissectionregion through access device 310. Access device 310 may be anyconvenient device, such as a conventional retractor tube. Access device310 as shown in FIG. 3A has an inner diameter of 7.0 mm and an outerdiameter of 9.5 mm. At this stage, orientation of camera 320 is biasedto one side (left side in figure). During insertion, the electrode 340on the side opposite the viewing field of the camera (right side infigure) is distally translated so that it emerges distally from thedistal tip of the device 300. Also during insertion, the distallytranslated electrode 340 is activated by supplying RF current andirrigating conducting fluid, resulting in tissue dissection duringinsertion of the device. For further tissue dissection on the side towhich the camera is biased (left side in figure), the electrode 340 onthe same side as the viewing field of the camera (left side in figure)is distally translated so that it emerges laterally from the endoscopeprobe on the proximal side of the camera. While being translated, thesame electrode (left side in figure) is activated by supplying RFcurrent and irrigating conducting fluid, resulting in tissue dissection.At this point, the entire end of the device 300 may be translatedproximally and distally until the desired tissue dissection is obtained.When finished with tissue dissection at the first location, the devicemay be rotated 180 degrees and further tissue removed using the stepsdescribed above.

FIG. 3B shows an example cross-section of the distal end of a device 300similar to that in FIG. 3A, except that it includes additionalirrigation lumens 370 (outer diameter 1.2 mm) in addition to theirrigation lumens 350 (dimensions of 1.5 mm×0.9 mm) associated with theelectrodes 340 (dimensions 2.5 mm×1.1 mm). Also, the geometry of theaspiration tube is hexagonal rather than rectangular to maximize use ofspace for this geometry (dimensions 4.2 mm×2.3 mm). The drawing is toscale, and shows another example of what can be integrated at the distalend of a device having a 6.6 mm outer. As shown, the cross section ofthe camera 320 is overlapping with other elements as in FIG. 3A, whichshows how the camera cross-section only occupies space at the mostdistal portion of the device. Overlapping portions of other crosssections, including the light sources, one of the electrodes, and theaspiration tube, would be terminated or diverted laterally beforereaching the proximal end of the camera. Operating this device mayinclude the same steps as described above in connection with the deviceof FIG. 3A, except that additional irrigation could be used to helpflush out dissected tissue and to clean the camera lens using theadditional irrigation lumens 370.

FIG. 3C shows an example cross-section of the distal end 300 of a devicesimilar to that in FIG. 3B, except that the orientation one of theelectrodes 340 is reversed and the geometry of the aspiration tube 360is trapezoidal rather than hexagonal to maximize use of space for thisgeometry. The drawing is to scale, and shows another example ofcomponents that can be integrated into a 6.6 mm outer diameter devicedistal end. In FIG. 3C, the dimensions of the components are the same asthat of FIG. 3B, with the exception that irrigation lumens 370 have anouter diameter of 1.1 mm, the dimensions of aspiration lumen 360 are 4.2mm×2.7 mm, the dimensions of electrodes 340 are 2.5 mm×1.1 mm and thedimensions of electrode irrigation lumens 350 are 1.5 mm×0.9 mm. As inthe devices shown in FIGS. 3A and 3B, the camera cross section isoverlapping with other elements, which shows how the cameracross-section 320 only occupies space at the most distal portion of theprobe. Overlapping portions of other cross sections, including the lightsources, one of the electrodes, and the aspiration tube, would beterminated or diverted laterally before reaching the proximal end of thecamera 320. Operating this device may include the same steps asdescribed above in connection with the device of FIGS. 3A and 3B.

FIG. 3D shows an example cross-section of the distal end 300 of a devicethat is similar to that in FIG. 3C, except that only one electrode 340(dimensions 5.4 mm diameter×0.35 mm thick) is used and it is much largerthan the electrode present in the device shown in FIG. 3C. The electrodeirrigation lumen is also dimensioned differently, having dimensions of1.5 mm×0.6 mm. In FIG. 3C, integrated camera 320 is shown with cameracables 380 (having dimensions of (1.5 mm×0.8 mm). Also, the geometry ofthe aspiration lumen is a semi-circular rather than trapezoidal tomaximize use of space for this geometry, where the dimensions of theaspiration lumen are 3.4 mm×2.1 mm. The drawing is to scale, and showsan example of the components that can be integrated at the distal end ofa device that has a 6.6 mm outer diameter. The device is shown presentin an access tube having a 7.2 mm inner diameter and a 9.5 mm outerdiameter. In FIG. 3D, the camera 320 cross section is overlapping withother elements as in FIGS. 3A to 3C, demonstrating that the camera 320cross-section only occupies space at the most distal portion of theprobe. Overlapping portions of other cross sections, including the lightsources and the aspiration tube, would be terminated or divertedlaterally before reaching the proximal end of the camera. Operating thisdevice may include the same steps as described above in connection withthe device of FIGS. 3A to 3C, except that the single electrode servesthe function of both electrodes in FIGS. 3A to 3C. The electrode isdistally translated only a short distance for distal cutting, and thenit is distally translated farther to cause it to extend laterally to theside viewed by the camera for tissue dissection on that side.

FIG. 3E shows an example cross-section of the distal probe tip similarto that in FIG. 3D, except that one of the irrigation channels isreplaced by a probe tool 390, having an outer diameter of 1.2 mm, whichis employed to manipulate tissue and expose target tissue regions forvisualization and/or modification by a tissue modifier, such as theelectrode device 340. The drawing is to scale, and shows another exampleof components that can be integrated at the distal end of a devicehaving a 6.6 mm outer diameter. Operating this device may include thesame steps as described above in connection with the device of FIGS. 3Ato 3D, except that the probe is also available for probing the tissuedissection region and for assisting in desired tissue dissection.

FIG. 4 provides a side view of a device according to an embodiment ofthe invention, where the device includes a side-viewing integratedcamera at its distal end. In FIG. 4, device 400 includes integratedcamera 410 having a side-viewing or biased lens 420, which provides afield of view which includes components from both the forward and sideviews of the device. As shown, the side-viewing camera is angled at adegree ranging from 15 to 65° relative to the longitudinal axis of theelongated member Device 400 also includes an integrated tissue cutter430 (e.g., in the form of an RF electrode) and integrated light source435. Device 400 is shown in relation to intervertebral disc 440, wherethe distal end of the device 400 extends through the annulus fibrosis450 into the nucleus pulposus 460.

FIG. 5 provides a side view of a device 500 according to an embodimentof the invention, where the device includes a side-viewing integratedcamera 510 at its distal end and two steerable electrodes 520 and 525.In FIG. 4, device 500 includes integrated camera 510 having aside-viewing or biased lens 520. Device 500 also includes an integratedelectrodes 530 and 535 which are steerable (erg., being fabricated froma shape-memory material) and integrated light source 540. Device 500 isshown in relation to intervertebral disc 540, where the distal end ofthe device 500 extends through the annulus fibrosis 450 into the nucleuspulposus 460.

FIGS. 6A and 6B are isometric views of an embodiment of the distal endof a tissue modification device illustrating the invention inserted intothe intervertebral disc space. The tissue modification device 600includes an elongated member 610 inserted through the disc annulus 620into the nucleus pulposus 630 of the intervertebral disc space. Thetissue modification device 600 also includes an RF electrode 640extended from the distal end of guidetubes 650, which are extended fromthe distal end of the elongated member 610. The guidetubes 650 areextended from the distal end of the elongated member 610 and have acurved shape, which facilitates access of the RF electrode 640 to theentire intervertebral disc space. The tissue modification device 600also includes an integrated CMOS visualization-element 660 at the distalend of the elongated member 610.

FIGS. 6A and 6B provide views of an RF electrode that is steerable atits distal end. In the embodiment depicted in FIGS. 6A and 6B, thesteering functionality of the RF electrode is provided by a shape-memoryelement in conjunction with a guidetube. The term “shape-memory” as usedherein refers to a material that can return to its original shape afterbeing deformed. In certain embodiments, the shape-memory elementcomprises a shape-memory alloy, such as, but not limited to, anickel-titanium (e.g., NITINOL) alloy, a copper-zinc-aluminum-nickelalloy, a copper-aluminum-nickel alloy, or the like. For example, thesteering functionality of the RF electrode can be provided by wirescomprising a shape-memory alloy. The shape-memory wires can be attachedto the RF electrode such that when the RF electrode is extended from thedistal end of the elongated member, the shape-memory wires take on apredetermined conformation, thus moving the RF electrode intosubstantially the same conformation. In certain cases, the shape-memoryelement is provided in conjunction with a guidetube. The guidetube canbe a tube (i.e., a cylinder with a hollow central lumen) provided withinthe elongated member for housing the RF electrode and for guiding thedirection of the RF electrode. Thus, the RF electrode can be providedwithin the central lumen of the guidetube. The guidetube can be composedof any convenient biocompatible material, such as plastic, rubber,metal, and the like. The guidetube can be provided with one or moreshape-memory elements, such as wires comprising a shape-memory alloy, asdescribed above. In certain embodiments, the guidetube is a shape-memoryguidetube, such as a guidetube comprising a shape-memory alloy.

In some cases, the guidetube is slidably positioned in the elongatedmember, and may be extended from the distal end of the elongated member.In some cases, the shape-memory guidetube has a curved shape whenextended from the distal end of the elongated member, such that theguidetube extends at an angle from the longitudinal axis of theelongated member. For example, when the guidetube is fully extended fromthe distal end of the elongated member, the guidetube may form an arcshape where the guidetube comprises an arc of 1° to 360°, such as 30° to180°, including 60° to 120°. As described above, the guidetube can beprovided with an RF electrode in the central lumen of the guidetube. Insome instances, the guidetube is configured to facilitate the RFelectrode's access to the entire intervertebral disc space. In certaininstances, accessibility to the entire IVD space is facilitated byarticulation of one or more of the RF electrode, the guidetube, and theelongated member. In addition, the RF electrode can be slidablypositioned in the guidetube, and may be extended from the distal end ofthe guidetube. The elongated member, the RF electrode and/or theguidetube can be independently rotated, providing additionalaccessibility within the IVD space.

In certain embodiments, the tissue modification device includes two ormore guidetubes, where the guidetubes are slideably translateable withrespect to the elongated member. In some cases, the guidetubes areslideably translateable with respect to each other, which facilitatesextending the RF electrode at an angle from the longitudinal axis of theelongated member or deforming the electrode tip into a new shape orconfiguration. Thus, one guidetube can be extended or retracted withrespect to the distal end of the elongated member independent of theother guidetube(s). For instance, the movement of each guidetube can becontrolled by the user, such that the user can extend, retract or steereach guidetube individually.

In some cases, the RF electrode comprises a wire slidably positioned ina shape-memory guidetube that is slidably positioned in the elongatedmember. In certain instances, the RF electrode comprises an exposedportion positioned between first and second ends, where the first andsecond ends are each positioned in a shape-memory guidetube. By“exposed” is meant that a portion of the RF electrode is able to makeelectrical contact with the desired target tissue. In these cases, thefirst and second ends are linearly translatable, where the first andsecond ends are translatable in unison, such that the first and secondends can be extended and retracted from the distal end of the elongatedmember at the same rate. In other instances, the first and second endsare linearly translatable with respect to each other, such that thefirst and second ends can be extended and retracted from the distal endof the elongated member at different rates or to different positions ofextension from the distal end of the elongated member. This facilitatesthe movement of the exposed portion of the RF electrode at an angle fromthe longitudinal axis of the elongated member. For example, when the RFelectrode is extended from the distal end of the elongated member, theangle between the RF electrode and the longitudinal axis of theelongated member can be from 1° to 270°, such as 30° to 180°, including60° to 120°.

As shown in FIGS. 6A and 6B, the RF electrode 640 is a U-shapedstructure that includes a distal cutting end (the exposed region),bounded on each side by a ceramic member. This U-shaped configuration isfurther illustrated in FIG. 6E. The ceramic members 617 flanking eachside of the distal cutting end 619 may be joined (e.g., such that theyhave a cross-bar configuration as shown in FIGS. 6A and 68) or beseparate component from each other (e.g., as shown in FIG. 6E). Thesecomponents may be fabricated from any convenient ceramic material,including but not limited to alumina, such as STEATITE™ alumina, MAECOR™alumina, and the like. In FIG. 6E, the extended length of region 619 mayvary, ranging from 2 to 20 mm, such as 2 to 10 mm and including 2 to 6mm. The diameter of the wire making up region 619 may vary, and incertain embodiments is 180 μm, such as 150 μm or less, such as 130 μm orless, such as 100 μm or less, such as 80 μm or less. While the distalcutting end or region 619 may be fabricated from a variety of materials,in some instances this portion of the electrode is fabricated from amaterial that is different from the material of the electrode wires 621.Materials of interest from which the distal cutting end 619 may befabricated include, but are not limited to tungsten, tungsten alloys,e.g., tungsten rhenium, steel, tungsten coated with noble metals, suchas Pt, Au, etc., and the like.

FIG. 6C provides a view of the distal end of device that is analogous tothat shown in FIGS. 6A and 6B. FIG. 6C shows how a variety of componentsincluding an integrated CMOS visualization sensor 660, irrigation lumens665, aspiration lumen 670, and steerable RF electrode 640 can beincorporated into the distal end of an elongated member having an outerdiameter that is 7.0 mm or less, such as 6.5 mm or less. Electrode 640is made up of electrode wires extending from electrode guidetubes 650.Separating the electrode wires from the distal cutting end 690 areceramic electrode crimp elements 680. Electrode wires 640 and guidetubes650 are shown in an extended configuration in FIG. 6C but eachindependently may be fabricated from a shape memory material so as toassume a curved configuration (as shown in FIGS. 6A and 6B) andtherefore impart steerability to the RF electrode. As shown in FIG. 6C,aspiration lumen 670 opens to the side of the device 600 and ispositioned just proximal of the CMOS visualization sensor 660 so thatall of the disparate components may be integrated at the distal end ofthe device.

FIG. 6D provides a three-dimensional view of one embodiment of a distalend of tissue modification device 600 (having a 6.5 mm outer dimension)of the invention. In FIG. 6D, the distal end of the device includes andintegrated circular CMOS visualization sensor 605 and integrated LED610. Also shown is a first forward facing irrigation lumen 615 and asecond irrigation lumen 617 which is slightly extended from the distalend and is side facing so that fluid emitted from lumen 617 is flowedacross CMOS visualization sensor 605 to clean the sensor of debris, whenneeded. Also shown is an aspiration lumen 625 positioned proximal theirrigation lumens 615 and 617 and integrated CMOS visualization sensor605, where the aspiration lumen 605 is configured to aspirate fluid andtissue debris from a target tissue site during use. The distal endfurther includes an integrated steerable RF electrode assembly 655. RFelectrode assembly 655 includes NITINOL shape memory guide tubes 645extending from insulated (e.g., RF shielded) guide lumens 642. The RFelectrode further includes a tungsten cutting wire 665 joined at eachend to a NITINOL shape memory electrode wire 663 by a ceramic arc stop675. As shown, the diameter of the cutting wire 665 is smaller than thediameter of the electrode wires 663, where the difference in size mayvary and may range from 100 to 500 μm, such as 300 to 400 μm.

FIGS. 1A and 1B, reviewed above, provide different views of a deviceaccording to an embodiment of the invention, where the device includes adistal end as shown in FIG. 6D. FIG. 7 provides a cutaway view of thedevices shown in FIGS. 1A and 1B. As shown in FIG. 7, the deviceincludes trigger element 125 which translates the guidetubes relative tothe distal end of the elongated member. Also shown is thumbwheel 130which provides for manual movement of the electrode relative to thedistal end. The cutaway view of FIG. 7 shows mechanical actuator 180which provides for linear translation of electrode 190 positioned at thedistal end of the elongated member.

Tissue modification devices of the invention are configured to behand-held. Accordingly, in certain instances the tissue modificationdevices have a mass that is 1.5 kg or less, such as 1 kg or less,including 0.5 kg or less, e.g., 0.25 kg or less.

Systems

Aspects of the subject invention include tissue modification systems,where the systems include a tissue modification device, e.g., asdescribed above, operatively connected to one or more extra-corporealcontrol units (i.e., extra-corporeal controllers). Extra-corporealcontrol units may include a number of different components, such aspower sources, irrigation sources, aspiration sources, image dataprocessing components, image display components (such as monitors,printers, and the like), data processors, e.g., in the form ofcomputers, data storage devices, e.g., floppy disks, hard drives,CD-ROM, DVD, flash memory, etc., device and system controls, etc.

An example of a system according to an embodiment of the invention isshown in FIG. 8. In FIG. 8 the system includes hand-held tissuemodification device 800 and extra-corporeal control unit 850. Hand-helddevice 800 includes distal end 810 and handle 820 configured to be heldin the hand of an operator. Positioned at the distal end 810 are theintegrated visualization and tissue modification components (as well asother components), as shown by cross-section 830. Extra-corporealcontrol unit 850 includes image display 860 (e.g., a liquid crystaldisplay monitor), video digital signal processor 870, energy source 880(e.g., configured to operate an RF tissue modification member) andirrigation/aspiration system 890. The hand-held device 800 andextra-corporeal control unit 850 are operatively connected to each otherby a cable.

FIG. 9 provides a diagrammatic view of the architecture of a systemaccording to one embodiment of the invention and how the variouscomponents of the system may interact with a user, such as a surgeon,during use. In FIG. 9, extra-corporeal control unit 910 includes a videoprocessing unit 911, an RF electrode power source 912, an irrigationsource 913 and an aspiration source 914. Each of these components isoperatively connected to electrical controls 915, with which the user990 may interact to operate the system as desired. Also shown is tissuemodification device 950 which includes an integrated visualizationsensor 951, an RF electrode 952, an irrigation lumen 953, an aspirationlumen 954 and an articulation mechanism 955. The tissue modificationdevice 950 provides a number of functionalities 960, including tissuedissection 961, tissue removal 962, tissue discrimination 963 andaccessibility 964. The system provides numerous user interfaceopportunities 930; including image display 931, tactile feedback 932 andmechanical controls 933.

Within a given system, the integrated distal end visualizationsub-system may have a variety of different configurations. FIG. 10provides an example of an embodiment of an integrated visualizationsub-system that includes a distal end CMOS visualization sensor. Asshown in FIG. 10, visualization sub-system 1000 includes distal end CMOSvisualization sensor 1010 that includes lens housing 1015 componentoperatively coupled to integrated circuit component 1020. As shown inthe figure, lens housing 1015 includes a lens set 1016. Also shown atthe distal end is LED 1018 which provides illumination for a targettissue location during use. Integrated circuit component 1020 includesCMOS sensor integrated circuit 1021 and rigid printed circuit board1022. The sub-components of lens housing/light source component 1015 areoperatively coupled to flexible cable 1030 which provides for operativeconnection of the CMOS visualization system at the distal end of thedevice via the handle. 1040 to the video processing sub-system 1050. Inthe handle 1040 the flexible cable operatively connects to a shieldedcable 1052 which provides for RF isolation. As shown in FIG. 10, thevarious components are shielded from RF, e.g., by coating the elementswith a conductive material which is then connected to a ground. Forexample, lens housing 1015 and cable 1030 are RF shielded. RF shieldedcable 1052 connects to video processing sub-system 1050 which includes avariety of functional blocks, such as host controller 1051 (coupled toPC 1061), digital signal processor 1052 (coupled to LCD 1062) and CMOSvisualization sensor bridge 1053. As shown in FIG. 10, video processingsub-system 1050 is ground to earth 1072 by connection to metal case1070.

Systems of the invention may include a number of additional componentsin addition to the tissue modification devices and extra-corporealcontrol units, as described above. Additional components may includeaccess port devices; root retractors; retractor devices, systemcomponent fixation devices; and the like; etc. Of interest are systemsthat further access devices as described in co-pending U.S. applicationSer. Nos. 12/269,770; 12/269,772; and 12/269,775; the disclosures ofwhich are herein incorporated by reference.

Methods

Aspects of the subject invention also include methods of imaging and/ormodifying an internal target tissue of a subject. Accordingly, aspectsof the invention further include methods of imaging an internal tissuesite with tissue modification devices of the invention. A-variety ofinternal tissue sites can be imaged with devices of the invention. Incertain embodiments, the methods are methods of imaging anintervertebral disc in a minimally invasive manner. For ease ofdescription, the methods are now primarily described further in terms ofimaging IVD target tissue sites. However, the invention is not solimited, as the devices may be used to image a variety of distincttarget tissue sites.

With respect to imaging an intervertebral disc or portion thereof, e.g.,exterior of the disc, nucleus pulposus, etc., embodiments of suchmethods include positioning a distal end of a minimally invasiveintervertebral disc imaging device of the invention in viewingrelationship to an intervertebral disc or portion of there, e.g.,nucleus pulposus, internal site of nucleus pulposus, etc. By viewingrelationship is meant that the distal end is positioned within 40 mm,such as within 10 mm, including within 5 mm of the target tissue site ofinterest. Positioning the distal end in viewing device in relation tothe desired target tissue may be accomplished using any convenientapproach, including through use of an access device, such as a cannulaor retractor tube, which may or may not be fitted with a trocar, asdesired. Following positioning of the distal end of the imaging devicein viewing relationship to the target tissue, the target tissue, erg.,intervertebral disc or portion thereof, is imaged through use of theillumination and visualization elements to obtain image data. Image dataobtained according to the methods of the invention is output to a userin the form of an image, e.g., using a monitor or other convenientmedium as a display means. In certain embodiments, the image is a stillimage, while in other embodiments the image may be a video.

In certain embodiments, the methods include a step of tissuemodification in addition to the tissue viewing. For example, the methodsmay include a step of tissue removal, e.g., using a combination oftissue cutting and irrigation or flushing. For example, the methods mayinclude cutting a least a portion of the tissue and then removing thecut tissue from the site, e.g., by flushing at least a portion of theimaged tissue location using a fluid introduced by an irrigation lumenand removed by an aspiration lumen.

The internal target tissue site may vary widely. Internal target tissuesites of interest include, but are not limited to, cardiac locations,vascular locations, orthopedic joints, central nervous system locations,etc. In certain cases, the internal target tissue site comprises spinaltissue.

The subject methods are suitable for use with a variety of mammals.Mammals of interest include, but are not limited to: race animals, e.g.horses, dogs, etc., work animals, e.g. horses, oxen etc., and humans. Insome embodiments, the mammals on which the subject methods are practicedare humans.

An example of a method which employs the device depicted in FIG. 3Aincludes the following steps. First the distal end 300 of the device isintroduced into the target tissue dissection region through accessdevice 310. Access device 310 may be any convenient device, such as aconventional retractor tube. Access device 310 as shown in FIG. 3A hasan inner diameter of 7.0 mm and an outer diameter of 9.5 mm. At thisstage, orientation of camera 320 is biased to one side (left side infigure). During insertion, the electrode 340 on the side opposite theviewing field of the camera (right side in figure) is distallytranslated so that it emerges distally from the distal tip of the device300. Also during insertion, the distally translated electrode 340 isactivated by supplying RF current and irrigating conducting fluid,resulting in tissue dissection during insertion of the device. Forfurther tissue dissection on the side to which the camera is biased(left side in figure), the electrode 340 on the same side as the viewingfield of the camera (left side in figure) is distally translated so thatit emerges laterally from the endoscope probe on the proximal side ofthe camera. While being translated, the same electrode (left side infigure) is activated by supplying RF current and irrigating conductingfluid, resulting in tissue dissection. At this point, the entire end ofthe device 300 may be translated proximally and distally until thedesired tissue dissection is obtained. When finished with tissuedissection at the first location, the device may be rotated 180 degreesand further tissue removed using the steps described above.

Utility

The subject tissue modification devices and methods find use in avariety of different applications where it is desirable to image and/ormodify an internal target tissue of a subject while minimizing damage tothe surrounding tissue. The subject devices and methods find use in manyapplications, such as but not limited to surgical procedures, where avariety of different types of tissues may be removed, including but notlimited to; soft tissue, cartilage, bone, ligament, etc. Specificprocedures of interest include, but are not limited to, spinal fusion(such as Transforaminal Lumbar Interbody Fusion (TLIF)), total discreplacement (TDR), partial disc replacement (PDR), procedures in whichall or part of the nucleus pulposus is removed from the intervertebraldisc (IVD) space, arthroplasty, and the like. As such, methods of theinvention also include treatment methods, e.g., where a disc is modifiedin some manner to treat an existing medical condition. Treatment methodsof interest include, but are not limited to: annulotomy, nucleotomy,discectomy, annulus replacement, nucleus replacement, and decompressiondue to a bulging or extruded disc. Additional methods in which theimaging devices find use include those described in United StatesPublished Application No. 20080255563.

In certain embodiments, the subject devices and methods facilitate thedissection of the nucleus pulposus while minimizing thermal damage tothe surrounding tissue. In addition, the subject devices and methods canfacilitate the surgeon's accessibility to the entire region interior tothe outer shell, or annulus, of the IVD, while minimizing the risk ofcutting or otherwise causing damage to the annulus or other adjacentstructures (such as nerve roots) in the process of dissecting andremoving the nucleus pulposus.

Furthermore, the subject devices and methods may find use in otherprocedures, such as but not limited to ablation procedures, includinghigh-intensity focused ultrasound (HIFU) surgical ablation, cardiactissue ablation, neoplastic tissue ablation (e.g. carcinoma tissueablation, sarcoma tissue ablation, etc.), microwave ablation procedures,and the like. Yet additional applications of interest include, but arenot limited to: orthopedic applications, e.g., fracture repair, boneremodeling, etc., sports medicine applications, e.g., ligament repair,cartilage removal, etc., neurosurgical applications, and the like.

Devices of the invention may provide variable tactile feedback to theoperator depending on tissue type. For example, in embodiments where adistal end structure, such as a tissue modifier (e.g., a RF electrode)is linearly translated by a mechanical linear actuator (e.g., asdescribed above), the operator may experience different tactileproperties depending on the type of tissue that is being contacted bythe linearly translating distal end structure. These different tactileproperties may then be employed by the user to differentiate betweendifferent types of tissue. In other words, devices of invention mayprovide different sensations to an operator, such as a surgeon, duringuse depending on the nature of the tissue with the distal end of thedevice is in contact. As such, devices and methods of the invention alsofind use in tissue discrimination applications, where the devices areemployed to determine the particular nature of the internal tissue withwhich the distal end of the device is in contact, e.g., whether thedistal end of the device is in contact with soft tissue, cartilage,bone, etc.

As reviewed above, in some embodiments synchronization of the tissuemodifier's modulation waveform with its linear translation waveformprovides additional benefits. For instance, rapid retraction of theelectrode from hard tissue that it encounters will leave the tissuemodifier physically separated from the hard tissue by a gap as thetissue modifier approaches the proximal extreme position. In someembodiments, the tissue modifier tip is activated only when the tissuemodifier is at or near the proximal extreme position, as mentionedabove. This has the effect of preferentially delivering the tissuemodification energy to soft, compliant tissue as opposed to hard, stifftissue. Stated otherwise, this provides tissue discrimination based onelastic modulus. In the case of spinal surgery applications requiringremoval of nuclear material, such as fusion, total disc replacement, andpartial disc replacement, synchronization of the modulation waveformwith the linear translation waveform facilitates the delivery of tissuemodification energy to the nucleus pulposus (soft, compliant tissue)while minimizing the delivery of tissue modification energy to the discannulus (hard, stiff tissue) and the endplates of the vertebral bodies(hard, stiff tissue). In addition, cyclic linear translation of thetissue modifier helps to prevent a condition where the electrode sticksto tissue as it ablates it, resulting in increased thermal effects tothe surrounding tissue, ineffective or discontinuous tissue dissection,buildup of charred or otherwise modified tissue on the tissue modifiertip, or a combination thereof. Additionally, cyclic linear translationof the tissue modifier helps chop the dissected tissue into smallerpieces, thus facilitating aspiration of the dissected tissue.

Kits

Also provided are kits for use in practicing the subject methods, wherethe kits may include one or more of the above devices, and/or componentsof the subject systems, as described above. The kit may further includeother components, e.g., guidewires, access devices, fluid sources, etc.,which may find use in practicing the subject methods. Various componentsmay be packaged as desired, e.g., together or separately.

In addition to above mentioned components, the subject kits may furtherinclude instructions for using the components of the kit to practice thesubject methods. The instructions for practicing the subject methods aregenerally recorded on a suitable recording medium. For example, theinstructions may be printed on a substrate, such as paper or plastic,etc. As such, the instructions may be present in the kits as a packageinsert, in the labeling of the container of the kit or componentsthereof (i.e., associated with the packaging or subpackaging) etc. Inother embodiments, the instructions are present as an electronic storagedata file present on a suitable computer readable storage medium, e.g.CD-ROM, diskette, etc. In yet other embodiments, the actual instructionsare not present in the kit, but means for obtaining the instructionsfrom a remote source, e.g. via the internet, are provided. An example ofthis embodiment is a kit that includes a web address where theinstructions can be viewed and/or from which the instructions can bedownloaded. As with the instructions, this means for obtaining theinstructions is recorded on a suitable substrate.

Although the foregoing invention has been described in some detail byway of illustration and example for purposes of clarity ofunderstanding, it is readily apparent to those of ordinary skill in theart in light of the teachings of this invention that certain changes andmodifications may be made thereto without departing from the spirit orscope of the appended claims. It is also to be understood that theterminology used herein is for the purpose of describing particularembodiments only, and is not intended to be limiting, since the scope ofthe present invention will be limited only by the appended claims.

Accordingly, the preceding merely illustrates the principles of theinvention. It will be appreciated that those skilled in the art will beable to devise various arrangements which, although not explicitlydescribed or shown herein, embody the principles of the invention andare included within its spirit and scope. Furthermore, all examples andconditional language recited herein are principally intended to aid thereader in understanding the principles of the invention and the conceptscontributed by the inventors to furthering the art, and are to beconstrued as being without limitation to such specifically recitedexamples and conditions. Moreover, all statements herein recitingprinciples, aspects, and embodiments of the invention as well asspecific examples thereof, are intended to encompass both structural andfunctional equivalents thereof. Additionally, it is intended that suchequivalents include both currently known equivalents and equivalentsdeveloped in the future, i.e., any elements developed that perform thesame function, regardless of structure. The scope of the presentinvention, therefore, is not intended to be limited to the exemplaryembodiments shown and described herein. Rather, the scope and spirit ofpresent invention is embodied by the appended claims.

1. A tissue modification device comprising: an elongated member having adistal end dimensioned to be passed through a minimally invasive bodyopening, wherein the distal end comprises an integrated visualizationsensor and tissue modifier.
 2. The tissue modification device accordingto claim 1, wherein the integrated visualization sensor comprises a lensand an integrated circuit.
 3. The tissue modification device accordingto claim 2, wherein the visualization sensor is a CMOS device.
 4. Thetissue modification device according to claim 2, wherein thevisualization sensor is a CCD device
 5. The tissue modification deviceaccording to claim 1, wherein the device further comprises an integratedarticulation mechanism that imparts steerability to at least one of thevisualization sensor, the tissue modifier and the distal end of theelongated member.
 6. The tissue modification device according to claim1, wherein the distal end of the elongate member is dimensioned to bepassed through a Cambin's triangle.
 7. The tissue modification deviceaccording to claim 6, wherein the distal end of the elongate member hasan outer diameter of 7.5 mm or less.
 8. The tissue modification deviceaccording to claim 7, wherein the distal end of the elongate member hasan outer diameter of 7.0 mm or less.
 9. The tissue modification deviceaccording of claim 8, wherein the distal end of the elongate member hasan outer diameter of 5.0 mm or less.
 10. The tissue modification deviceaccording to claim 1, wherein the distal end of the elongate memberfurther comprises an integrated illuminator.
 11. The tissue modificationdevice according to claim 10, wherein the illuminator is a fiber-opticilluminator.
 12. The tissue modification device according to claim 10,wherein the illuminator is a light emitting diode.
 13. The tissuemodification device according to claim 1, wherein the tissue modifiercomprises an electrode.
 14. The tissue modification device according toclaim 1, wherein at least one of the visualization sensor and tissuemodifier are moveable relative to the distal end of the elongate member.15. The tissue modification device according to claim 1, wherein thedistal end of the elongate member further comprises an irrigator and anaspirator.
 16. The tissue modification device according to claim 15,wherein the aspirator is located proximal of the integratedvisualization sensor.
 17. The tissue modification device according toclaim 15, wherein the aspirator comprises a port having across-sectional area that is 33% or more of the cross-sectional area ofthe distal end of the elongate member.
 18. The tissue modificationdevice according to claim 1, wherein the elongated member is rigid. 19.The tissue modification device according to claim 1, wherein the tissuemodification device is configured to modify an intervertebral disctissue.
 20. The tissue modification device according to claim 1, whereinthe device is configured as a disposable.
 21. The tissue modificationdevice according to claim 1, wherein the device comprises an operatinghandle positioned at the proximal end.
 22. The tissue modificationdevice according to claim 21, wherein the distal end of the elongatedmember is rotatable about its longitudinal axis when a significantportion of the operating handle is maintained in a fixed position.
 23. Asystem comprising: (a) an elongated member having a distal enddimensioned to be passed through a minimally invasive body opening,wherein the distal end comprises an integrated visualization sensor andtissue modifier; and (b) an extracorporeal controller operativelycoupled to the proximal end of the elongated member.
 24. The systemaccording to claim 23, wherein the system further comprises an imagedisplayer for displaying to a user images obtained by the visualizationsensor.
 25. The system according to claim 23, wherein the system furthercomprises a minimally invasive access tube.
 26. A method of modifying aninternal target tissue of a subject, the method comprising: (a)positioning distal end of a tissue modification device comprising anelongated member having a distal end dimensioned to be passed through aminimally invasive body opening, wherein the distal end comprises anintegrated visualization sensor and tissue modifier in operable relationto the internal target tissue; and (b) modifying the internal targettissue with the tissue modifier.
 27. The method according to claim 26,wherein the internal target tissue site comprises spinal tissue.
 28. Themethod according to claim 26, wherein the method is a method of removingnucleus pulposus tissue from an intervertebral disc.